Today at Google’s developer conference, MySpace said it would use Google Gears to power search and sort functions for its email, giving users a highly sought-after functionality at little cost to MySpace infrastructure. The move is a great one for MySpace, which is really pulling out all the stops in its rivalry with Facebook.

Making social networking email more user-friendly and searchable was a top concern among Facebook users who questioned Mark Zuckerberg during his keynote at the South by Southwest event in March, so I’m guessing MySpace users also felt pain in that area, since the inbox functions are so similar. So MySpace is clearly following user demand with this announcement. It’s now left up to users to decide if they will use Gears. They will receive a prompt on their MySpace pages letting them know about the option.

Gears is an open-source development platform that an individual user downloads for free. The program then allows applications running in the web browser to access the user’s own CPU and storage. The enables offline access to web applications and richer web applications without breaking the site owner’s infrastructure. Sites need to be optimized to work with Gears, which MySpace has done. Other sites using Gears include Google’s Reader and Docs, as well as Zoho.

Because it offloads some of the processing power and caching to the user’s desktop, MySpace’s decision to use Gears has the added bonus of reducing some of the hardware demands required for MySpace to improve its email. I’ll offer more details on that aspect of after I chat with MySpace this afternoon.

Update: Allen Hurff, SVP of engineering at MySpace, talked a bit about the bandwidth and server savings for the social network, but also pointed out that using Google Gears or Adobe Air could allow for new services such as keeping months or years worth of status updates on a user’s computer or lead to an off-browser email client.

As for the user experience, he emphasized that one of the results of off loading processing to the user’s computer means information loads faster because the user isn’t waiting for it to hit a server and come back. He pointed out that most computers don’t use all of their processing power and memory right now, which means this isn’t an intrusive service on a machine.

As for questions about security and keeping email on public machines, he said MySpace could one day choose to offer an encrypted version of the data stored on machines, but said it would slow down the service. However, for those deciding to check email on public computers, and are worried their email will linger, users are given the option to wipe their data.